Description of the Related Art
The reduction of engine wear and friction in internal combustion engines continues to be of importance especially with increased fuel costs and the limited future supplies of hydrocarbon reserves. Reduction of engine wear and friction is addressed through the use of appropriate lubricating oil applications. However, engine wear reduction and friction control also often necessitates the formulation of fuels such as diesel fuel and gasoline with enhanced lubricity characteristics. One class of compounds capable of improving fuel economy is the substituted hydrocarbons having 12 to 36 carbon atoms. These hydrocarbons are typically substituted with surface active functional groups including carboxylic acids, alcohols, and amines.
U.S. Pat. No. 6,224,642 disclose compositions that include a polyetheramine and substituted hydrocarbons selected from the group that includes fatty acids, fatty acid amides, fatty acid esters, hydrocarbyl substituted succinic acids, hydrocarbyl substituted succinic anhydrides, amide, imide or ester derivatives of, hydrocarbyl substituted succinic anhydrides, and alkoxylated amines. The enhanced lubricity characteristics of fuel compositions containing these additives were demonstrated by the reduction of the wear scar of the fuel in the high frequency reciprocation rig using test method ASTM D6079-97.
U.S. Pat. No. 4,617,026 disclose a method to reduce fuel consumption in a gasoline engine by including a fuel additive that is an ester having at least one free hydroxyl group and formed from a monocarboxylic acid and a glycol or trihydric alcohol. The monocarboxylic acid has about 12 to 30 carbon atoms. The example cited was glycerol mono-oleate which derived for the fatty acid oleic acid.
U.S. Pat. No. 4,236,898 discloses fuel compositions which reduce friction between sliding metal surfaces in internal combustion engines from the addition to the hydrocarbon fuel a sulfurized fatty acid amide, ester, or ester-amides. Exemplary examples of fatty acids include oleic, linoleic, elaidic, erucic and tall oil fatty acids.
U.S. Pat. Nos. 6,835,217 and 6,743,266 disclose a fuel composition comprising the reaction product of a natural or synthetic oil and at least one alkanolamine and at least one fuel detergent. Exemplary examples of natural oils are the naturally occurring oils that are derived from animal or plant sources. Such oils are mixed C6-C22 fatty acid esters.
U.S. Pat. No. 6,203,584 disclose fuel compositions that include aliphatic hydrocarbyl substituted amines and/or polyetheramines and esters of carboxylic acids and polyhydric alcohols to improve fuel economy. Wherein, the carboxylic acid has from one to about 50 carbon, atoms and the polyhydric alcohol has from about 2 to about 50 carbon atoms and from about 2 to about 6 hydroxy groups. Suitable carboxylic acids include saturated and unsaturated fatty acids such as capric, lauric, palmitic, stearic, linoleic, and linolenic acids.
U.S. Pat. No. 4,729,769 discloses a motor fuel composition containing a minor amount of a detergent additive being the reaction product of a C6-C20 fatty acid ester and a mono- or di-(hydroxy hydrocarbonyl) amine. Typical fatty acid esters used include the esters of lauric, palmitic, stearic, oleic, and linoleic acids.
U.S. Pat. Nos. 5,958,089; 6,280,488; 5,858,028; 5,833,722; 5,882,364; and 5,833,722 disclose fuel compositions that include a fuel oil having a low sulfur content and an mono- and poly-carboxylic acid or the ester of a polyhydric alcohol and a mono- or poly-carboxylic acid to enhance lubricity of the fuel. Exemplary mono- and poly-carboxylic acids include the fatty acids oleic and linoleic acids as well as the oligomers of polyunsaturated fatty acids such as dilinoleic acid.
Solving the Low Temperature
U.S. Pat. No. 6,866,690 describes a friction modifier for use in fuels that is n-butyl amine isostearate. The use of this friction modifier in combination with a detergent package permits increased fuel efficiency without increasing the incidence of IVD deposits.
Unfortunately, the hydrocarbons of these friction modifiers typically are low molecular weight unsaturated or mono-unsaturated hydrocarbons in order to provide the frictional characteristics necessary to make them friction modifiers. Unsaturated low molecular weight saturated or mono-unsaturated hydrocarbons have waxy characteristics and encounter poor solubility at low temperatures. Stable fuel additive concentrates are required to facilitate injection of the concentrate into fuel. This requires the concentrate to be in the form of a low viscosity, homogeneous liquid.
U.S. Pat. No. 5,968,211 filed May 26, 1998 (Schilowitz) discloses gasoline lubricity additive selected from the group consisting of saturated and unsaturated fatty acids, oligomerized saturated and unsaturated fatty acids, esters of such fatty acids and of oligomerized fatty acids and mixtures thereof. In order to improve the low temperature properties of a concentrate containing the lubricity additive in relatively high concentration, a compatibilizer, which remains liquid to a temperature of at least 0° C., and selected from the group consisting of an alcohol, an amine or mixtures of alcohols and amines was used. All working examples in this patent use a commercial, sample of a mixture of tall oil fatty acids available from Petrolite Ltd. known as Tolad 9103. Tolad 9103 is defined in the patent to comprise a mixture of polymerized fatty acids, non-polymerized fatty acids and heavy aromatic naphtha and requires a compatibilizer that is liquid at 0° C.
U.S. Pat. No. 6,524,353 discloses a fuel additive composition composed of the reaction product of a mixture of fatty acid esters having 6 to 20 carbon atoms and a low molecular weight ester having 3 to 10 carbon atoms with mono- or di-hydroxy alkyl amines. The inclusion of the low molecular weight ester reactant is to improve the low temperature properties of the friction modifiers.
U.S. Pat. No. 6,277,158 discloses an additive concentrate for use in fuels comprising an ashless friction modifier selected from n-butylamine oleate, tall oil fatty acid, and mixtures thereof along with a deposit inhibitor and a fluidizer. This patent discloses good low temperature stability when using a commercial sample of a mixture of tall oil fatty acids available from Petrolite Ltd. as Tolad 9103. Tolad, 9103 comprises a mixture of polymerized fatty acids, non-polymerized fatty acids and heavy aromatic naphtha. Unfortunately, examples in the patent indicate that similar low temperature enhancement is not obtained with friction modifiers such as glycerol mono oleate, polyol ester of oleic acid, a fatty amide, and a sorbitan mono oleate.
U.S. Patent Application 2002/0174597 discloses a gasoline additive concentrate comprising a solvent, an alkoxylated fatty amine, and a partial ester having at least one free hydroxyl group. The solvent providing an additive concentrate that is homogenous for facile transferring and handling of the concentrate composition. The solvent is selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, C2-C10 alcohols, and mixtures of two or more thereof. The preferred choice of solvent is that's allowing the concentrate composition to be liquid at a temperature from about 0° C. to minus 18° C. For some terminal application, additive concentrates must be fluid at temperatures below minus 18° C.
It has now been found that the fuel additive concentrate composition that remains fluid at below ambient temperatures, such as 0° C. to −18° C., of the present invention when used in a fuel composition provides a way to reduce fuel consumption in gasoline internal combustion engines. The benefits of this invention are both economic and environmental and include reduced fuel costs, fuel conservation, and reduced emission of greenhouse gases.